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cos(4*a) если a=-1

Выражение, которое надо упростить:

Решение

Вы ввели [src]
cos(4*a)
$$\cos{\left(4 a \right)}$$
cos(4*a)
Подстановка условия [src]
cos(4*a) при a = -1
подставляем
cos(4*a)
$$\cos{\left(4 a \right)}$$
cos(4*a)
$$\cos{\left(4 a \right)}$$
переменные
a = -1
$$a = -1$$
cos(4*(-1))
$$\cos{\left(4 (-1) \right)}$$
cos(4)
$$\cos{\left(4 \right)}$$
cos(4)
Численный ответ [src]
cos(4*a)
cos(4*a)
Степени [src]
 -4*I*a    4*I*a
e         e     
------- + ------
   2        2   
$$\frac{e^{4 i a}}{2} + \frac{e^{- 4 i a}}{2}$$
exp(-4*i*a)/2 + exp(4*i*a)/2
Раскрыть выражение [src]
         2           4   
1 - 8*cos (a) + 8*cos (a)
$$8 \cos^{4}{\left(a \right)} - 8 \cos^{2}{\left(a \right)} + 1$$
   4         4           2       2   
cos (a) + sin (a) - 6*cos (a)*sin (a)
$$\sin^{4}{\left(a \right)} - 6 \sin^{2}{\left(a \right)} \cos^{2}{\left(a \right)} + \cos^{4}{\left(a \right)}$$
cos(a)^4 + sin(a)^4 - 6*cos(a)^2*sin(a)^2
Тригонометрическая часть [src]
   1    
--------
sec(4*a)
$$\frac{1}{\sec{\left(4 a \right)}}$$
   /pi      \
sin|-- + 4*a|
   \2       /
$$\sin{\left(4 a + \frac{\pi}{2} \right)}$$
      1      
-------------
   /pi      \
csc|-- - 4*a|
   \2       /
$$\frac{1}{\csc{\left(- 4 a + \frac{\pi}{2} \right)}}$$
       2     
1 - tan (2*a)
-------------
     2       
  sec (2*a)  
$$\frac{- \tan^{2}{\left(2 a \right)} + 1}{\sec^{2}{\left(2 a \right)}}$$
        2     
-1 + cot (2*a)
--------------
       2      
1 + cot (2*a) 
$$\frac{\cot^{2}{\left(2 a \right)} - 1}{\cot^{2}{\left(2 a \right)} + 1}$$
   2      /        2     \
sin (2*a)*\-1 + cot (2*a)/
$$\left(\cot^{2}{\left(2 a \right)} - 1\right) \sin^{2}{\left(2 a \right)}$$
       2     
1 - tan (2*a)
-------------
       2     
1 + tan (2*a)
$$\frac{- \tan^{2}{\left(2 a \right)} + 1}{\tan^{2}{\left(2 a \right)} + 1}$$
   2      /       2     \
cos (2*a)*\1 - tan (2*a)/
$$\left(- \tan^{2}{\left(2 a \right)} + 1\right) \cos^{2}{\left(2 a \right)}$$
  1      2        cos(4*a)
- - + cos (2*a) + --------
  2                  2    
$$\cos^{2}{\left(2 a \right)} + \frac{\cos{\left(4 a \right)}}{2} - \frac{1}{2}$$
        1    
1 - ---------
       2     
    cot (2*a)
-------------
        1    
1 + ---------
       2     
    cot (2*a)
$$\frac{1 - \frac{1}{\cot^{2}{\left(2 a \right)}}}{1 + \frac{1}{\cot^{2}{\left(2 a \right)}}}$$
      /      pi\  
 2*tan|2*a + --|  
      \      4 /  
------------------
       2/      pi\
1 + tan |2*a + --|
        \      4 /
$$\frac{2 \tan{\left(2 a + \frac{\pi}{4} \right)}}{\tan^{2}{\left(2 a + \frac{\pi}{4} \right)} + 1}$$
          /         4     \
   2      |    4*sin (2*a)|
cos (2*a)*|1 - -----------|
          |        2      |
          \     sin (4*a) /
$$\left(- \frac{4 \sin^{4}{\left(2 a \right)}}{\sin^{2}{\left(4 a \right)}} + 1\right) \cos^{2}{\left(2 a \right)}$$
         2        
      sec (2*a)   
1 - --------------
       2/      pi\
    sec |2*a - --|
        \      2 /
------------------
       2          
    sec (2*a)     
$$\frac{- \frac{\sec^{2}{\left(2 a \right)}}{\sec^{2}{\left(2 a - \frac{\pi}{2} \right)}} + 1}{\sec^{2}{\left(2 a \right)}}$$
          /       2/      pi\\
          |    cos |2*a - --||
   2      |        \      2 /|
cos (2*a)*|1 - --------------|
          |         2        |
          \      cos (2*a)   /
$$\left(1 - \frac{\cos^{2}{\left(2 a - \frac{\pi}{2} \right)}}{\cos^{2}{\left(2 a \right)}}\right) \cos^{2}{\left(2 a \right)}$$
             2                        
/       2   \     4    /       2     \
\1 - tan (a)/ *cos (a)*\1 - tan (2*a)/
$$\left(- \tan^{2}{\left(a \right)} + 1\right)^{2} \cdot \left(- \tan^{2}{\left(2 a \right)} + 1\right) \cos^{4}{\left(a \right)}$$
               /         4     \
   2/pi      \ |    4*sin (2*a)|
sin |-- + 2*a|*|1 - -----------|
    \2       / |        2      |
               \     sin (4*a) /
$$\left(- \frac{4 \sin^{4}{\left(2 a \right)}}{\sin^{2}{\left(4 a \right)}} + 1\right) \sin^{2}{\left(2 a + \frac{\pi}{2} \right)}$$
                   2                    
/   2         2   \         2       2   
\cos (a) - sin (a)/  - 4*cos (a)*sin (a)
$$- 4 \sin^{2}{\left(a \right)} \cos^{2}{\left(a \right)} + \left(- \sin^{2}{\left(a \right)} + \cos^{2}{\left(a \right)}\right)^{2}$$
/              /pi      \           
|   0      for |-- + 4*a| mod pi = 0
<              \2       /           
|                                   
\cos(4*a)          otherwise        
$$\begin{cases} 0 & \text{for}\: \left(4 a + \frac{\pi}{2}\right) \bmod \pi = 0 \\\cos{\left(4 a \right)} & \text{otherwise} \end{cases}$$
/         4     \               
|    4*sin (2*a)|               
|1 - -----------|*(1 + cos(4*a))
|        2      |               
\     sin (4*a) /               
--------------------------------
               2                
$$\frac{\left(- \frac{4 \sin^{4}{\left(2 a \right)}}{\sin^{2}{\left(4 a \right)}} + 1\right) \left(\cos{\left(4 a \right)} + 1\right)}{2}$$
       2/pi      \
    csc |-- - 2*a|
        \2       /
1 - --------------
         2        
      csc (2*a)   
------------------
     2/pi      \  
  csc |-- - 2*a|  
      \2       /  
$$\frac{1 - \frac{\csc^{2}{\left(- 2 a + \frac{\pi}{2} \right)}}{\csc^{2}{\left(2 a \right)}}}{\csc^{2}{\left(- 2 a + \frac{\pi}{2} \right)}}$$
         4     
    4*sin (2*a)
1 - -----------
        2      
     sin (4*a) 
---------------
         4     
    4*sin (2*a)
1 + -----------
        2      
     sin (4*a) 
$$\frac{- \frac{4 \sin^{4}{\left(2 a \right)}}{\sin^{2}{\left(4 a \right)}} + 1}{\frac{4 \sin^{4}{\left(2 a \right)}}{\sin^{2}{\left(4 a \right)}} + 1}$$
/      1         for 2*a mod pi = 0
|                                  
|        2                         
<-1 + cot (2*a)                    
|--------------      otherwise     
|       2                          
\1 + cot (2*a)                     
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{\cot^{2}{\left(2 a \right)} - 1}{\cot^{2}{\left(2 a \right)} + 1} & \text{otherwise} \end{cases}$$
/            1               for 2*a mod pi = 0
|                                              
<   2      /        2     \                    
|sin (2*a)*\-1 + cot (2*a)/      otherwise     
\                                              
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\left(\cot^{2}{\left(2 a \right)} - 1\right) \sin^{2}{\left(2 a \right)} & \text{otherwise} \end{cases}$$
             2                
/       2   \  /       2     \
\1 - tan (a)/ *\1 - tan (2*a)/
------------------------------
                     2        
        /       2   \         
        \1 + tan (a)/         
$$\frac{\left(- \tan^{2}{\left(a \right)} + 1\right)^{2} \cdot \left(- \tan^{2}{\left(2 a \right)} + 1\right)}{\left(\tan^{2}{\left(a \right)} + 1\right)^{2}}$$
/      1         for 2*a mod pi = 0
|                                  
|         1                        
|-1 + ---------                    
<        2                         
|     tan (2*a)                    
|--------------      otherwise     
|     2                            
\  csc (2*a)                       
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{-1 + \frac{1}{\tan^{2}{\left(2 a \right)}}}{\csc^{2}{\left(2 a \right)}} & \text{otherwise} \end{cases}$$
/            1               for 2*a mod pi = 0
|                                              
|   2      /         1    \                    

            
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\left(-1 + \frac{1}{\tan^{2}{\left(2 a \right)}}\right) \sin^{2}{\left(2 a \right)} & \text{otherwise} \end{cases}$$
/      1         for 2*a mod pi = 0
|                                  
|         1                        
|-1 + ---------                    
|        2                         
<     tan (2*a)                    
|--------------      otherwise     
|        1                         
|1 + ---------                     
|       2                          
\    tan (2*a)                     
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{-1 + \frac{1}{\tan^{2}{\left(2 a \right)}}}{1 + \frac{1}{\tan^{2}{\left(2 a \right)}}} & \text{otherwise} \end{cases}$$
       2/      pi\
    cos |2*a - --|
        \      2 /
1 - --------------
         2        
      cos (2*a)   
------------------
       2/      pi\
    cos |2*a - --|
        \      2 /
1 + --------------
         2        
      cos (2*a)   
$$\frac{1 - \frac{\cos^{2}{\left(2 a - \frac{\pi}{2} \right)}}{\cos^{2}{\left(2 a \right)}}}{1 + \frac{\cos^{2}{\left(2 a - \frac{\pi}{2} \right)}}{\cos^{2}{\left(2 a \right)}}}$$
         2        
      sec (2*a)   
1 - --------------
       2/      pi\
    sec |2*a - --|
        \      2 /
------------------
         2        
      sec (2*a)   
1 + --------------
       2/      pi\
    sec |2*a - --|
        \      2 /
$$\frac{- \frac{\sec^{2}{\left(2 a \right)}}{\sec^{2}{\left(2 a - \frac{\pi}{2} \right)}} + 1}{\frac{\sec^{2}{\left(2 a \right)}}{\sec^{2}{\left(2 a - \frac{\pi}{2} \right)}} + 1}$$
                //     1        for a mod pi = 0\
/       2     \ ||                              |
\1 - tan (2*a)/*|<1 + cos(4*a)                  |
                ||------------     otherwise    |
                \\     2                        /
$$\left(- \tan^{2}{\left(2 a \right)} + 1\right) \left(\begin{cases} 1 & \text{for}\: a \bmod \pi = 0 \\\frac{\cos{\left(4 a \right)} + 1}{2} & \text{otherwise} \end{cases}\right)$$
       2/pi      \
    csc |-- - 2*a|
        \2       /
1 - --------------
         2        
      csc (2*a)   
------------------
       2/pi      \
    csc |-- - 2*a|
        \2       /
1 + --------------
         2        
      csc (2*a)   
$$\frac{1 - \frac{\csc^{2}{\left(- 2 a + \frac{\pi}{2} \right)}}{\csc^{2}{\left(2 a \right)}}}{1 + \frac{\csc^{2}{\left(- 2 a + \frac{\pi}{2} \right)}}{\csc^{2}{\left(2 a \right)}}}$$
/                1                   for 2*a mod pi = 0
|                                                      
|     4       2    /         1    \                    
<4*cos (a)*tan (a)*|-1 + ---------|      otherwise     
|                  |        2     |                    
|                  \     tan (2*a)/                    
\                                                      
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\4 \left(-1 + \frac{1}{\tan^{2}{\left(2 a \right)}}\right) \cos^{4}{\left(a \right)} \tan^{2}{\left(a \right)} & \text{otherwise} \end{cases}$$
/             1                for 2*a mod pi = 0
|                                                
|          /         2      \                    
<   2      |      sin (4*a) |                    
|sin (2*a)*|-1 + -----------|      otherwise     
|          |          4     |                    
\          \     4*sin (2*a)/                    
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\left(-1 + \frac{\sin^{2}{\left(4 a \right)}}{4 \sin^{4}{\left(2 a \right)}}\right) \sin^{2}{\left(2 a \right)} & \text{otherwise} \end{cases}$$
/         1           for 2*a mod pi = 0
|                                       
|          2                            
|       csc (2*a)                       
|-1 + --------------                    
<        2/pi      \                    
|     csc |-- - 2*a|                    
|         \2       /                    
|-------------------      otherwise     
|        2                              
\     csc (2*a)                         
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{\frac{\csc^{2}{\left(2 a \right)}}{\csc^{2}{\left(- 2 a + \frac{\pi}{2} \right)}} - 1}{\csc^{2}{\left(2 a \right)}} & \text{otherwise} \end{cases}$$
/                        /pi      \           
|        0           for |-- + 4*a| mod pi = 0
|                        \2       /           
|                                             
|      /      pi\                             
< 2*cot|2*a + --|                             
|      \      4 /                             
|------------------          otherwise        
|       2/      pi\                           
|1 + cot |2*a + --|                           
\        \      4 /                           
$$\begin{cases} 0 & \text{for}\: \left(4 a + \frac{\pi}{2}\right) \bmod \pi = 0 \\\frac{2 \cot{\left(2 a + \frac{\pi}{4} \right)}}{\cot^{2}{\left(2 a + \frac{\pi}{4} \right)} + 1} & \text{otherwise} \end{cases}$$
/         1           for 2*a mod pi = 0
|                                       
|        2/      pi\                    
|     sec |2*a - --|                    
|         \      2 /                    
|-1 + --------------                    
<          2                            
|       sec (2*a)                       
|-------------------      otherwise     
|      2/      pi\                      
|   sec |2*a - --|                      
|       \      2 /                      
\                                       
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{-1 + \frac{\sec^{2}{\left(2 a - \frac{\pi}{2} \right)}}{\sec^{2}{\left(2 a \right)}}}{\sec^{2}{\left(2 a - \frac{\pi}{2} \right)}} & \text{otherwise} \end{cases}$$
/                1                  for 2*a mod pi = 0
|                                                     
|               /         2      \                    
|               |      sin (4*a) |                    
<(1 - cos(4*a))*|-1 + -----------|                    
|               |          4     |                    
|               \     4*sin (2*a)/                    
|---------------------------------      otherwise     
\                2                                    
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{\left(-1 + \frac{\sin^{2}{\left(4 a \right)}}{4 \sin^{4}{\left(2 a \right)}}\right) \left(- \cos{\left(4 a \right)} + 1\right)}{2} & \text{otherwise} \end{cases}$$
/            1               for 2*a mod pi = 0
|                                              
|     2    /         1    \                    
|4*tan (a)*|-1 + ---------|                    
|          |        2     |                    
<          \     tan (2*a)/                    
|--------------------------      otherwise     
|                   2                          
|      /       2   \                           
|      \1 + tan (a)/                           
\                                              
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{4 \left(-1 + \frac{1}{\tan^{2}{\left(2 a \right)}}\right) \tan^{2}{\left(a \right)}}{\left(\tan^{2}{\left(a \right)} + 1\right)^{2}} & \text{otherwise} \end{cases}$$
/                 1                    for 2*a mod pi = 0
|                                                        
|               /          2        \                    
|   2/      pi\ |       cos (2*a)   |                    

            
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\left(\frac{\cos^{2}{\left(2 a \right)}}{\cos^{2}{\left(2 a - \frac{\pi}{2} \right)}} - 1\right) \cos^{2}{\left(2 a - \frac{\pi}{2} \right)} & \text{otherwise} \end{cases}$$
/       1          for 2*a mod pi = 0
|                                    
|         2                          
|      sin (4*a)                     
|-1 + -----------                    
|          4                         
<     4*sin (2*a)                    
|----------------      otherwise     
|        2                           
|     sin (4*a)                      
|1 + -----------                     
|         4                          
\    4*sin (2*a)                     
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{-1 + \frac{\sin^{2}{\left(4 a \right)}}{4 \sin^{4}{\left(2 a \right)}}}{1 + \frac{\sin^{2}{\left(4 a \right)}}{4 \sin^{4}{\left(2 a \right)}}} & \text{otherwise} \end{cases}$$
                //       1         for a mod pi = 0\
                ||                                 |
                ||              2                  |
/        1    \ ||/        2   \                   |
|1 - ---------|*|<\-1 + cot (a)/                   |
|       2     | ||---------------     otherwise    |
\    cot (2*a)/ ||              2                  |
                || /       2   \                   |
                \\ \1 + cot (a)/                   /
$$\left(1 - \frac{1}{\cot^{2}{\left(2 a \right)}}\right) \left(\begin{cases} 1 & \text{for}\: a \bmod \pi = 0 \\\frac{\left(\cot^{2}{\left(a \right)} - 1\right)^{2}}{\left(\cot^{2}{\left(a \right)} + 1\right)^{2}} & \text{otherwise} \end{cases}\right)$$
/         1           for 2*a mod pi = 0
|                                       
|          2                            
|       cos (2*a)                       
|-1 + --------------                    
|        2/      pi\                    
|     cos |2*a - --|                    
<         \      2 /                    
|-------------------      otherwise     
|          2                            
|       cos (2*a)                       
| 1 + --------------                    
|        2/      pi\                    
|     cos |2*a - --|                    
\         \      2 /                    
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{\frac{\cos^{2}{\left(2 a \right)}}{\cos^{2}{\left(2 a - \frac{\pi}{2} \right)}} - 1}{\frac{\cos^{2}{\left(2 a \right)}}{\cos^{2}{\left(2 a - \frac{\pi}{2} \right)}} + 1} & \text{otherwise} \end{cases}$$
/         1           for 2*a mod pi = 0
|                                       
|        2/      pi\                    
|     sec |2*a - --|                    
|         \      2 /                    
|-1 + --------------                    
|          2                            
<       sec (2*a)                       
|-------------------      otherwise     
|        2/      pi\                    
|     sec |2*a - --|                    
|         \      2 /                    
| 1 + --------------                    
|          2                            
\       sec (2*a)                       
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{-1 + \frac{\sec^{2}{\left(2 a - \frac{\pi}{2} \right)}}{\sec^{2}{\left(2 a \right)}}}{1 + \frac{\sec^{2}{\left(2 a - \frac{\pi}{2} \right)}}{\sec^{2}{\left(2 a \right)}}} & \text{otherwise} \end{cases}$$
/                         1                            for 2*a mod pi = 0
|                                                                        
|                 //     0        for 2*a mod pi = 0\                    

            
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\left(\cot^{2}{\left(2 a \right)} - 1\right) \left(\begin{cases} 0 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{- \cos{\left(4 a \right)} + 1}{2} & \text{otherwise} \end{cases}\right) & \text{otherwise} \end{cases}$$
/         1           for 2*a mod pi = 0
|                                       
|          2                            
|       csc (2*a)                       
|-1 + --------------                    
|        2/pi      \                    
|     csc |-- - 2*a|                    
<         \2       /                    
|-------------------      otherwise     
|          2                            
|       csc (2*a)                       
| 1 + --------------                    
|        2/pi      \                    
|     csc |-- - 2*a|                    
\         \2       /                    
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{\frac{\csc^{2}{\left(2 a \right)}}{\csc^{2}{\left(- 2 a + \frac{\pi}{2} \right)}} - 1}{\frac{\csc^{2}{\left(2 a \right)}}{\csc^{2}{\left(- 2 a + \frac{\pi}{2} \right)}} + 1} & \text{otherwise} \end{cases}$$
/                          1                             for 2*a mod pi = 0
|                                                                          
|                 //      0         for 2*a mod pi = 0\                    
|                 ||                                  |                    
|                 ||       2                          |                    

            
$$\begin{cases} 1 & \text{for}\: 2 a \bmod \pi = 0 \\\left(\cot^{2}{\left(2 a \right)} - 1\right) \left(\begin{cases} 0 & \text{for}\: 2 a \bmod \pi = 0 \\\frac{4 \cot^{2}{\left(a \right)}}{\left(\cot^{2}{\left(a \right)} + 1\right)^{2}} & \text{otherwise} \end{cases}\right) & \text{otherwise} \end{cases}$$
Piecewise((1, Mod(2*a = pi, 0)), ((-1 + cot(2*a)^2)*Piecewise((0, Mod(2*a = pi, 0)), (4*cot(a)^2/(1 + cot(a)^2)^2, True)), True))